Abstract

WIDUP, R. and BARLAND, G. H. Effect of the location
of the numbers test on examiner decision rates in criminal
psychophysiological detection of deception tests. March
1994, Report No. DoDPI94-R-0015. United States Army Criminal
Investigation Command and Department of Defense Polygraph
Institute, Fort McClellan, AL 36205.

The U.S. Army Criminal
Investigation Command (USACIDC) conducted 251 psychophysiological
detection of deception (PDD) examinations on suspects
of criminal offenses in which a numbers (stim) test
was conducted between the first and second tests of the
main
test series, as is their standard procedure. Another
231 examinations were conducted in which the numbers
test was conducted prior to the first test of the main
test series. Study results suggest the location of
the numbers test had no effect on the inconclusive rate
or
the number of deception indicated (DI) and no deception
indicated (NDI) decisions.

Director's Foreword

This is another study wherein a field practitioner
served as the principle investigator (PI) in conducting
a field
research project. One of the technical issues in psychophysiological
detection of deception (PDD) has to do with the use
of a numbers test in the test sequence. Some examiners
use
it before the main test series; others use it after
the first test of the main test series; and others do
not
use it at all.

The results of this study support the position that
it does not matter if the numbers test is used before
or after the first test of the main test series as regard
to an effect on the inconclusive rate or the number of
deception indicated (DI) or no deception indicated (NDI)
diagnostic decisions.

This study did not, however, address the issue as to
the value of the numbers test as regard to whether such
a test actually improves the quality of the physiological
data collected and if that in turn produces higher diagnostic
accuracy. In other words, does a numbers test really
do what PDD examiners claim it will do? An analog study,
where ground truth is known, will be required to answer
this important question.